Method of manufacturing inductance-coils.



' W. FUNDILLER.

I METHODOF MANUFACTURING INDUCTANCE COILS. APPLICATION mzo sEPT.|z. 19H.

x 1,212,755' I I I fatentdJan. 16,1917.

Mt Wfl/iam Fond/Her y 7M fy q swarms PATENT, m n

' WILLIAM rename, or new roan, n. r., assienoms'r xssmi assrcmnrs, ro wssrm ELEG'I'BIG comm, mcoaroaarnn; a coaronarron or NEW roax.

METHOD OF WUFACTUBING IilTDUCTANQB-GOILB.

1 and its object is to maintain constant the inductances of the line windings during the process of manufacture of the coils.

The usual steps in the'manufacture of a loading coil are as follows: A very fine hard drawn iron wire is' given a thin coatin or film of insulating material and wound into a toroidal core, or-the core ma be formed I as and immediatel of unannealed iron latessimi arly coated. The core is then insu ated and insulated copliter wire wound threomusuall in sections.

the case of a phantom loading coil having air-gaps in its core, to which this invention is ciall applicable, the co per wire is plac d ih imYer and outer windihgsona plurality of core sections, say four, the inner winding on one quarter section being connected in series with the outer winding on the opposite quarter section. These two sectional windings to ther' constitute one of the line windings o the hantom system. After the inner sectiona windings are placed on the core, they are tested, compared and adjusted to a measured standard and compare to insure that they will offer the same inductanccs to the telephonic currents This is of the highest importance in order to meet the close balance uirements for a phantom loading coil. en the-outer sectional windingsare laced over. the inner windings and tested and adjusted in a similar manner. The wound coils are then'baked, preferably in a vacuum, in order to drive out the moisture from-the insulation .on the copper wires, immersed in insulating compound whic thoroughly imprefinates the windin Finally, after the co s are taken out 0 this bath of insulating material 'and cooled, they are placed in protecting cases and sealed by filling the cases with an insulating compound. It has been found in' that changes in the indu'ctances of t e' windings occur by reason following this. process Specification of Letters Patent. Application filed September 12, 1814. Berta; No. 861,400.

the winding inductances were of one with the other, in order.

Patented Jan. 16, 1917.

of the heating of the coil core in the bakin ovens sndin the hot insulatin compoun so that the careful testing and a justmentof little or no use. Furthermore, after the baking and the 'm re ating of the wound coils, it 1s impos sib et en to make any read'ustment of the inner sectional windings wit out'wholl removing the outer layers; The tearing own .of the coil,'in order to add to or remove turns from the inner windings, is objectionable because of high labor cost and loss due to the destructionof theouter windin It is of im ortance to obtain a. sta 1e magnetic condition of the core, more especially in phantom loading coils having airgaps, because. the proper fulfilment of the requirements for such coils necessitates the observance of a definite ratio of turns in the inner and outer sectional windings. Failure to observe this ratio of turns would result in an increased effective resistance to the sidecircuit connection of the phantom coil, and

would also result in crosstalk between the sides of the phantom circuit. It is highly desirable, therefore, that the inductances of sections of the finished the several windin loading coil shall the same as the fixed and measured value for which these winding sections were designed. Investigation of the difficulty in manufacture referred to led to the discovery that the chan ductance of the windings occurr s in inby reason of -a change in the initial permeability 7 of-the' material of the core, due 'to the heatwhich the core is. subsequently-sub'ected,

this in order that the hysteresis an eddy eurrent l in the iron core may not be increased more than absolutely aucv:

losses, it is noted, increase rapi y with increase of permeability of the iron,

ing' of the core when the coil is in the bak- .ing oven or when it is immersed in the hot no i ' '45 It has been "emo ist I ted l q i l g e frthe core i i thebaking' oven andjwlienjthe coil is dipped in the in-- and 'is ih eonsiias sew time 'Ithe"be essm aspossihle'.

"I the accompanying drawingi's shown in .cross-section aloadingjcoil and its i-nclos-v ,ing case to assist in an understaiiding ofthe invention. v v

Thecore 19f "the loading coil is best made up of unan ie'aled iron, and preferablyof a'fi 'ie-hard,drawn"iron wire"'wou'nd in such a way as 130* formarii g or toroid. Preferably i the core isfciiit atjdiametrically'opposite -"points sothat it"beco'ines' "a discontinuous toroidal coreof two sections "separated by air-gaps 5 The drawing illustrates a phantom loading coil having windings'2 to 9' inclusive, windings 2 to 5- being the inner sectional windings; and 6'to 9- the outer ones. .T he preliminarybaking-of the core material is preferably vd'onebefc'i're the wire is formed '20 into a core and before it is given a thin coating or-filni of insulationthis to avoid the probability of injury to. the insulation.

. After the core wire'is thus baked, insulated and formed 'ii'ito a"toroidal-core, the windings are placedloii the co're and the twogaps cut in {the core between adjacent windings.

' The inner sectional-- windings are tested and adjusted before the outer sectional windings ardgglaced "over them; and then. the outer win ngs are dippe insulating material. -'The temperature reachedbythe core in baking and 8 5 while-"immersed inv the insulatingniaterialshould not materially exceed and preferably should be'as nearly ual' as possible 'to the "reliiiiinary. core aking'fltemperature. Finall the coil is "inserted "in a protecting 40 case .10 and insulating'material ll poured in,.

in the mannerpreviouslystate'd; The core v f -.t m mg m reached durinfil'this latter step should'also benot Ygreater t an the preliminary core baki temperature."

I sulating compounds, does notfmaterially change theinitialpermeabilityof the core providedgthe" preliminaryjcore baking temperature is-not exceeded. Iii-fact, any reas'onable number of such limited heating op" "erati'ons my take pllace i without inateri chan "thefcore Y 'aracteristics and thereb5 fore wit oiit :alterin the win' ing inductances' from the v and measured value with-whichthey'had been compared.

*what 'islclaiinedis: niethed 50f manufacturin'g' :induccore material to a bakin semblin the said materia nto a' core, placv Iing win ings on the core, and=subsequeiitly 1 matel'y' the same as the preliminary temperature.

placed over-the innerones and. tested "and ad i1ste'd-,- all in the manner-previousl stated. The coil. is' then baked ,and'

drawn iron wire a bakin g tem 'ra'tuiet the wireinto'a core-win ingfthe 6. The

hat the substemperature, a

heating the coil at'atemperature 'a promki s- "2. The method of manufacturinginductance coils which consists in subjectingthe.

core "material to a baking temperature plac ing windings, on the "core, baking thh coil,

' and impregnating the coil in insulating,

compound, the maximum temperature of the v core during the bak ng and ipreg'nat'ing steps being approximately the same as. the

preliminary'core. baking temperature 3. The. method otmanufacturingflindue tancefcoils-which iii-subjecting the core material to a baking-temperaturqplacing a plurality of line. winding sections gon the core, comparing the inducta' 'icesi of the line winding sections with, fat-standard induc tance, and heating the .rcoil-at a erature r. I

approximately the same as the-pro imina core-baking te n rature. 'i 4. The meth of manufacturing, inductance coils which consists in siibjecting the-Q "core material to a temperature, coating the said material with';'aninsulating:-

film, assembling the said material into a, core, lacing windings on the; core, and heatso ing' t e coil at a temperature approximately,

.the same as the preliiniiiaryt-core baking" temperature. Y v5. The method of -manufacturing induc tance coils which consists-in subjecting hard formi-n 7 core with insulated wire and heating the coil ata temperature approximately: the same as the preliminary core baking into a core, the said baking-tempera ture being substantially the same as the.)

hi heat temperature to which the core is seiuently sub'ected in completing the" manu acture of t ecoih j. In witness whereof, I- hereunto subscribe my name this 11 day' of SeptemberA 'D.',

,- 'WILLIAM FONDILLER.

" Names tance coils which consistsin subjecti igthege,

method of manufacturing core'sl for inductance coils which sub 'jectin'g hard drawn al bakih g; I temperature, coating. said wire. with an :in- 1'05 sulating filmfand forming said 'coatedzwire z j 

